Study Of The Technology On LFM Signal Pulse Compression

The distance resolving power of radar is rest with the bandwidth of radar signal. The accumulation of time and bandwidth of common pulse radar signal is a constant, so it can not give attention to both the distance resolving power and the rate differentiation power. With the improvement on the system of radar , there is great enhancement on both the range and the distance differentiation power. This system is radar-pulse compression system, in which we use wide pulse so as to enhance the transmitting-power in average and the maximum range . When receiving, we obtain narrow pulse with pulse compression technology ,so as to increase the distance resolving power. As a result, we resolve the contradiction between the range and distance resolving power. The spectrum of LFM signal is close to rectangle .Besides that, the quadratic phase and the optional accumulation of time and bandwidth are also the characteristic of LFM signal . LFM signal can offer fine distance resolving power and the radial rate differentiation power, which makes it become into the main form of radar signal.This thesis mainly studies the radar signal digital pulse compression processing system in frequency,including the design of the structure of this system,the demonstration of the programme and simulation which is based on MATLAB. In this dissertation ,the methods of digital LFM pulse compression in frequency,the design of match-filter and side-lobes suppression filter,the algorithm of phase-coherent accumulation and its effect are analysed.To begin with ,the theory of radar signal pulse compression is studied.After that , the characteristic of the signal with great accumulation of time and bandwidth is analysed.And then , the thesis focuses on the advantages and disadvantages of the methods of LFM pulse compression on frequency or time.The resource and time which is used in the two programmes are estimated.And the method on frequency is chosen at last.In succession,the algorithm of FFT and the design of the match-filter and the window function are specified. Although the large quantity of data , the time of procession is limited by the algorithm of radix-4 FFT.Eight butterfly arithmetic operators are used simultaneously in the radix-4 FFT . It saves the time maximally in the limitation of resource. The match-filter and window function are multiplied into one part,so that the resource can be saved and the guideline can be satisfied.After that,the algorithm of phase-coherent accumulation is dissertated. Both the request of resource and time are satisfied.The whole system is analysed at last , and also the function of each module.Then it is tested by simulation.